My take on belts:

As we age I would say get a belt with suspenders to better distribute the load and also to fight the mid section gravity distortion. Also allows you to run a small hydration setup on your back which will keep you sharp and in the game.
Cobra buckle for sure. I have a plastic buckle on my old belt and I had a situation where it was half undone.
If you run a pistol go with the Safari Land retention system. Friends don?t let friends run Serpa.
For rifle mags I like the tacos but they add size and complexity, but they run AR/AK/FAL mags. Same story for pistol mags. But this is where I would improve and settle on dedicated AR and pistol pouches once I figure out what they are.
A small rolly Polly mag pouch is handy for quick changes or spares.
Don?t forget a blow out kit. If you are training stuff gets whacky.
And is this a dedicated training rig or a general rig? Either way set it up and modify and keep going until you like it.